The Program in Radiobiology and Radiotherapy (R&R) comprises a broadly based, multifaceted research effort in radiation therapy, radiation biology, radiological physics and related areas of tumor biology. This program has been an approved component of the Cancer Center Core Grant for over 20 years. Its long-term goal is to improve the treatment of cancer in general and in particular, the effectiveness of radiation therapy The program includes a broad spectrum of activity that extends from laboratory-based experimental research to clinical investigation and features investigators associated with eight departments. Some of the key themes include studies of carcinogenesis, genetic instability and cell growth control;elucidation of DNA repaii pathways;investigation of tumor hypoxia and testing of hypoxia-targeted cancer therapies in clinical trials molecular correlations with outcomes in radiation therapy, and improvements in radiation dosimetry, imaging and delivery. The majority of the members of the program have rich interactions with the Yale Cancer Cente (YCC) membership in several programs. Those interactions stimulate translational research that is in turr facilitated by other YCC Research Programs and by extensive use of Shared Resources. The numerous cancer-related grand rounds, seminars, meetings, and journal clubs sponsored by the YCC, along with the weekly Radiobiology Workshop and Journal Club and the weekly Therapeutic Radiology Grand Rounds sponsored by the program encourage the cooperation, mutual support, and cross stimulation among the component research teams, which leads to a more rapid and efficient application of the results of the research to clinical practice. Dr. Peter M. Glazer took over as Program Leader in 2002, replacing Dr. James J. Fischer, who had served as Program Leader since its inception. Dr. Patrick Sung, recruited to Yale in 2003, serves as co-Leader. Unde the new leadership, the Program has expanded to include a total of 25 faculty affiliated with nine departments and two schools, has played a role in recruiting three basic scientists and three physician investigators, anc has initiated renovation of 15,500 net square feet of laboratory space, partially funded by a $2.0 millior construction grant from the NIH awarded in 2003. Dr. Glazer also serves as PI of a T32 post-doctoral training grant in Radiation Therapy, Biology and Physics, which includes a number of YCC members both within anc outside of the Program. Since 1998, there have been 371 cancer-related publications, including 18% intra- anc 20% inter-programmatic collaborations. Overall, the 25 investigators associated with the program have peer reviewed funding of $4.1 M in annual direct costs ($6.4 M in annual total costs), including 17 R01s. Of this funding, $2.0 M (annual direct costs) comes from the NCI, including 10 R01s and the T32 training grant.